1. Field of the Invention
The present invention relates generally to outdoor electrical enclosures and, more particularly, to outdoor electrical enclosures employing a moisture-resistant structure. The invention also relates to moisture-resistant structures for outdoor electrical enclosures.
2. Background Information
Electrical equipment (e.g., without limitation, relays; circuit breakers; electric meters; transformers) used outdoors are typically housed within an enclosure, such as, for example, a housing, such as a box or cabinet, to protect the electrical equipment from the environment and to prevent electrical faults caused by moisture. The enclosure is often mounted, for example, within a prepared opening in the wall of a building.
To comply with weather-resistance standards established by the National Electrical Machinery Association (NEMA), including NEMA 3R standards, known prior art electrical enclosures typically comprise a weather-resistant housing made of folded sheet metal. Frequently, the housing includes a number of flanges, commonly referred to as nail flanges, which are structured to secure the housing in its installed position, for example, within the prepared opening in the wall of the building. The flanges of such electrical enclosures are typically fastened (e.g., without limitation, screwed; riveted; bolted; welded) to the housing in such a way that allows moisture to enter into both the outdoor electrical enclosure itself and the prepared opening in the wall in which it is mounted. This can have undesirable effects within the wall cavity of the building (e.g., without limitation, insulation damage; the development of mold) and, in the event moisture penetrates the enclosure housing, can lead to electrical faults and damage to the electrical equipment. Mold caused by dampness within the wall cavity could result in chronic health problems and ensuing litigation.
FIGS. 1 and 2 show an outdoor electrical enclosure that employs such flanges. The enclosure shown in FIG. 1 is a semi-flush metered panelboard 2 comprising a wall-mounted box enclosure 4 supporting, for example, electrical switching apparatus (e.g., without limitation, circuit switching devices and circuit interrupters such as circuit breakers, contactors, motor controllers and other load controllers) (not shown). Although not required, a meter 6 (FIG. 1) may provide a visual readout on the front cover 8 of the enclosure 4 of information indicative of electrical conditions related to the panelboard 2. The sides 10, 11 of the enclosure 4 have a number of flanges, such as side flanges 14, 15, respectively. The top 12 and bottom 13 of the enclosure 4 also include top and bottom flanges 16, 17, respectively. These flanges 14, 15, 16, 17 are typically fabricated from steel (e.g., without limitation, galvanized steel; painted steel).
As shown in FIG. 2, the flanges 14, 15, 16, 17 (one side flange 15 is shown on side 11 in FIG. 2) are separately manufactured, generally L-shaped components attached to the enclosure 4 by numerous fasteners 18 (e.g., without limitation, screws; bolts; rivets; welding). Moisture frequently seeps through gaps present between the L-shaped side flanges (e.g., 12, 15) and the top 12 and side 11, for example, of the enclosure 4 and also enters into the prepared wall opening in which the enclosure 4 is mounted (not shown).
To prevent moisture from entering an outdoor electrical enclosure, the flanges of some known outdoor electrical enclosures (not shown) are welded to the housing (not shown). However, the flanges of such designs are typically spot welded and, therefore, still permit moisture to seep between the gaps in between the spot welds (not shown) attaching the flanges to the enclosure.
In addition, it is believed that known outdoor electrical enclosures do not provide any adjustment of the flanges in relation to the enclosure housing or adjustment of the enclosure housing itself (e.g., without limitation, depth, width and height adjustments). This lack of adjustment results in the inability to correct any misalignment and can thereby create additional points of water entry into both the enclosure and the wall in which it is installed. For example, power is generally supplied to the electrical equipment within the outdoor electrical enclosure by electrical wiring disposed within conduit, which typically enters the enclosure housing at the back of the bottom end wall. Absent the ability to adjust the depth of the housing, the conduit projecting from the back thereof can prevent the housing from being pushed back completely within the prepared opening. Gaps resulting from a poor fit within the prepared opening provide yet another point of entry for moisture to penetrate the building wall.
There is a need, therefore, for a simplified, outdoor electrical enclosure and flange structure capable of improved moisture-resistance.
Accordingly, there is room for improvement in flange structures for outdoor electrical enclosures and in outdoor electrical enclosures employing flange structures.